Field of the Invention
The present invention relates to a device and a method for wirelessly transmitting a power capable of easily being carried by a user and wirelessly transmitting a power to a power receiving device regardless of time or location.
Description of the Background Art
In general, a power receiving device for supplying an operating power is attached to various mobile terminals such as a cellular phone or a PDA (Personal Digital Assistant).
The power receiving device receives a power supplied from an external charging device, and supplies the received power to the mobile terminal as the operating power.
The power receiving device may include a battery that is charged with the power, and a charging/discharging circuit that receives the power supplied from the external charging device to charge the battery with the power, and that discharges the power charged in the battery to supply the discharged power to the mobile terminal as the operating power.
As a method for electrically connecting the charging device with the power receiving device, a terminal connecting method which directly connects a power output terminal of the charging device to a power input terminal of the power receiving device through a cable and a connector is widely known.
The power output terminal of the charging device and the power input terminal of the power receiving device have different potentials from each other.
Accordingly, when a terminal of the charging device from which the power is output and a terminal of the power receiving device to which the power is input are connected to each other or are separated from each other, instantaneous discharging may be caused due to a potential difference.
The instantaneous discharging causes abrasion in the terminal of the charging device and the terminal of the power receiving device. Further, when a foreign substance exists in the terminal of the charging device or the terminal of the power receiving device, heat is generated in the foreign substance due to the instantaneous discharging, so that there is a concern that a negligent accident such as fire may occur.
Furthermore, the power charged in the battery of the power receiving device is naturally discharged to the outside through the terminal of the power receiving device due to moisture, so that a lifespan of the power receiving device may be shortened, and performance thereof may be degraded.
In recent years, in order to solve various problems of the terminal connecting method, a wireless power transmitting device that wirelessly transmits the power to the power receiving device has been proposed.
The wireless power transmitting device wirelessly transmits the power by using, for example, an electromagnetic induction method. The power receiving device receives the power that is wirelessly transmitted from the wireless power transmitting device, and charges the battery with the received power.
Much research and development has gone into allowing the wireless power transmitting device to stably transmit the power with a high efficiency in a wireless manner and allowing the power receiving device to receive the power transmitted from the wireless power transmitting device to charge the battery with the power.
The wireless power transmitting device is typically operated by an alternating current power input from the outside to wirelessly transmit the power to the power receiving device.
Accordingly, the wireless power transmitting device can wirelessly transmit the power to the power receiving device only in a place where the alternating current power is supplied from the outside, and does not wirelessly transmit the power to the power receiving device in a place where the alternating current power is not supplied.